random misfire- can't find the cure
12-01-2008, 12:46 PM
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random misfire- can't find the cure
hello so this is going to be a long read but hopefully someone can help
problem: my drives good under 3000 rpms and starts stuttering over that and i get misfires random, sometimes code come back 2 or 3 or 2 and 3 or 1 and 4 or 2 and 4 just random.... anyways heres my deal
1999 audi a4 quatrro 1.8t AEB
new motor built by me
hot comp check results in 160 +- 5% for all 4 cylinders (just did it 5 min ago after a 20miles or more ride) not losing coolant either...
checked timing 4 times both cam to cam (16 links and slotts lined up just as bently says) and cam gear to crank is good
new front O2 sensor
3 different new ICMs
4 different new sets of coilpacks
3 different new cts's
new maf (also have an extra cleaned one from junk yard)
new cam postion sensor
two different ecus (one chipped one not)
3 different sets of plugs NGK one step colder gapped at .028 for the chipped ecu, champions for the stock ecu also autolite
new k03 turbo
check for vac/boost leaks 7 differnt times, boost gauge read 20inHG at idle and it holds boost fines tilll 3000 rpms where i don't like to take it anymore.
so i started to think maybe my wires were cracked in the coilpack harness so i spliced in new ones and no luck....
then i thought throttle body alignment ( well i put a junk yard throttle body on) cleaned before install with a new gasket, then i aligned the throttle body with vag com, throttle adaptation status ok.....same misfires
so i guess what im trying to say is don't go buying parts till you find out what is exactly wrong, ive spent well over 2 g's in parts including the rebuilt with scat rods so i could go big turbo but not till i figure this out. In the long run i have all new parts anyways though....
my only next turn is to the fuel system, i will change the filter and try the "tecron" fix next, but if anyone has had similar problems and could chime it here it would be a great help
-Travis
ohh yes forgot to mention on all 3 of my new icms i did these two test for the icm (http://www.passatworld.com/forums/sh...d.php?t=133976 and https://forums.audiworld.com/a4/msgs/1594531.phtml) and i get the ohm meter reading an open circuit for all of the pin outs on the icms
(1 . ) reads the ohm meter for each pin out meaning open circuit
so i figured if all the pins have an open circuit wouldn't the car not run?? because like the 2nd link shows his circuit was open on number 2 causing misfires in number 2 only, mine are open for all cylinder/pinouts
i also tryed applying a 9v and a 12v batteries to see if i could get some resistance and no luck...idk
problem: my drives good under 3000 rpms and starts stuttering over that and i get misfires random, sometimes code come back 2 or 3 or 2 and 3 or 1 and 4 or 2 and 4 just random.... anyways heres my deal
1999 audi a4 quatrro 1.8t AEB
new motor built by me
hot comp check results in 160 +- 5% for all 4 cylinders (just did it 5 min ago after a 20miles or more ride) not losing coolant either...
checked timing 4 times both cam to cam (16 links and slotts lined up just as bently says) and cam gear to crank is good
new front O2 sensor
3 different new ICMs
4 different new sets of coilpacks
3 different new cts's
new maf (also have an extra cleaned one from junk yard)
new cam postion sensor
two different ecus (one chipped one not)
3 different sets of plugs NGK one step colder gapped at .028 for the chipped ecu, champions for the stock ecu also autolite
new k03 turbo
check for vac/boost leaks 7 differnt times, boost gauge read 20inHG at idle and it holds boost fines tilll 3000 rpms where i don't like to take it anymore.
so i started to think maybe my wires were cracked in the coilpack harness so i spliced in new ones and no luck....
then i thought throttle body alignment ( well i put a junk yard throttle body on) cleaned before install with a new gasket, then i aligned the throttle body with vag com, throttle adaptation status ok.....same misfires
so i guess what im trying to say is don't go buying parts till you find out what is exactly wrong, ive spent well over 2 g's in parts including the rebuilt with scat rods so i could go big turbo but not till i figure this out. In the long run i have all new parts anyways though....
my only next turn is to the fuel system, i will change the filter and try the "tecron" fix next, but if anyone has had similar problems and could chime it here it would be a great help
-Travis
ohh yes forgot to mention on all 3 of my new icms i did these two test for the icm (http://www.passatworld.com/forums/sh...d.php?t=133976 and https://forums.audiworld.com/a4/msgs/1594531.phtml) and i get the ohm meter reading an open circuit for all of the pin outs on the icms
(1 . ) reads the ohm meter for each pin out meaning open circuit
so i figured if all the pins have an open circuit wouldn't the car not run?? because like the 2nd link shows his circuit was open on number 2 causing misfires in number 2 only, mine are open for all cylinder/pinouts
i also tryed applying a 9v and a 12v batteries to see if i could get some resistance and no luck...idk
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